This market will destroy the bulls AND the bears before much longer. Very little actual liquidity and heavily dependent upon political decisions/central bank injections. It's just a recipe for monumental whipsaw and head scratching.
1) How many weeks ago are you talking about? 2) What would that buy signal have been based on? I've been in stocks for awhile, but what you said sounds like typical hindsight analysis. "Yeah, you should've invested back in November/December, when stocks were meandering around with no clear direction. We smart guys knew a rally was about to explode..." A short-term pullback in an uptrend is one of the best times to buy or add positions. However, you certainly need an exit plan. I wouldn't recommend putting your entire 401k into the market now with no plan to take profits or cut losses..
S&P500 etc daily charts indicate substantial selling ahead. This says it all... DOW weekly chart as of Feb 22 http://stockmarket618.files.wordpress.com/2012/02/2012-02-22_dowwk2.png
I bought months ago in early december figuring that the whole european scenario was old news. I can show you statements. I bought BAC a couple nickles above $5. You could've bought any time since then based on valuations. Actually the most profitable times are not to buy in an uptrend fyi but if your making money, then it makes no difference.